Physics

Nuclear and Atomic Physics

571 Questions

Nuclear and atomic physics explores the components and properties of the nucleus, including isotopes, radioactive decay, and fundamental forces. These concepts are essential for various competitive exams requiring a strong foundation in physics. The provided questions cover structural properties, mass, energy equivalence, and particle interactions.

Nucleus propertiesIsotopes and mass numberAlpha particle scatteringNuclear forcesMass energy equivalenceBeta particle emission

Nuclear and Atomic Physics Questions

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

The mass of $ _{3}^{7}{Li}$ is $0.042$ less than the mass of $3$ protons and $4$ neutrons. The binding energy per nucleon in $ _{3}^{7}{Li}$ is:

  1. $5.6 MeV$
  2. $56 MeV$
  3. $0.56 MeV$
  4. $560 MeV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The mass defect for $\displaystyle _3^7Li$  is $\displaystyle \Delta m = 0.042$  amu.
1 amu $\displaystyle =931.5$ MeV
Binding energy $\displaystyle = 0.042 \times 931.5 = 39.123$ MeV
Total number of nucleons in $\displaystyle _3^7Li$  is 7 (3 protons and 4 neutrons).
Binding energy per nucleon $\displaystyle =  \dfrac {39.123}{7} = 5.6$ MeV.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

The introduction of a neutron into the nuclear composition of an atom would lead to a change in:

  1. its atomic mass

  2. its atomic number

  3. the chemical nature of the atom

  4. number of the electron also
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The introduction of a neutron into the nuclear composition of an atom would lead to a change in its atomic mass.
However, its atomic number, the chemical nature of the atom and the number of the electron s will remain unchanged as they are related to the number of protons and are independent of the number of neutrons.

Note: The atomic mass is equal to the sum of the number of protons and the number of neutrons. Chemical properties depends on number of electrons which are equal to number of protons in neutral atom. They are also equal to atomic number.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

What is the order of density of neutron?

  1. $10^3$ kg/cc
  2. $10^6$ kg/cc
  3. $10^{12}$ kg/cc
  4. $10^2$ kg/cc
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Radius\ of\ neutron = 1\times 10^{-13}$
$\therefore$ volume $=\dfrac{4}{3}\times \pi  r^{3} = \frac{4}{3}\times \pi (1\times 10^{-13})^{3} = \dfrac{4}{3}\times \pi \times 10^{-39}$
Mass of neutron $=1.6\times 10^{-27}$
$\therefore$ Density $=\dfrac{mass}{volume}$ $=\dfrac{3\times 1.6\times 10^{-27}}{4\times \pi \times 10^{-39}} = \dfrac{4.8}{4\times \pi }\times 10^{12}$ kg/cc

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

The order (lowest to highest) of e/m (charge/mass) ratio for electron (e), proton (p), neutron (n) and alpha particle $(\alpha)$ is:

  1. $e, p, n, \alpha$
  2. $n, p, e, \alpha$
  3. $n, p, \alpha, e$
  4. $n, \alpha, p, e$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The increasing order (lowest to highest) of e/m (charge/mass) ratio is $ n < \alpha < p < e$.Neutron being neutral has zero charge and lowest e/m ratio. An electron has a unit charge but negligible mass. Hence, the electron has maximum e/m ratio.For an alpha particle, the e/m ratio is 2/4 or 0.5.For proton, e/m ratio is 1/1 or 1.


Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Which of the following doesn't have charge?

  1. Proton

  2. Neutron

  3. Electron

  4. Isotope

  5. Ion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Neutron has zero unit charge.
The neutron is a subatomic particle, symbol n or $n^0$, with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons, each with mass approximately one atomic mass unit, constitute the nucleus of an atom, and they are collectively referred to as nucleons

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Doubly magic nucleus is:

  1. $ _{ 82 }^{ 207 }{ Pb }$
  2. $ _{ 82 }^{ 206 }{ Pb }$
  3. $ _{ 82 }^{ 208 }{ Pb }$
  4. $ _{ 83 }^{ 209 }{ Bi }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Doubly magic nucleus is $\displaystyle _{ 82 }^{ 208 }{ Pb }$. It has 82 protons and $\displaystyle 208-82=126$ neutrons. 82 and 126 are magic numbers.

Multiple choice physics scientists inventions and inventors in science indian scientist: biography and achievements scientist and their achievements

Pick out the correct statement about the strong nuclear force from the following.
$S1$ : It is charge independent.
$S2$ : It is the strongest force in nature.
$S3$ : Its range is very large.
$S4$ : It is responsible for the stability of nuclei.

  1. $S1 and S3$
  2. $S1, S2 and S3$
  3. $S1, S2 and S4$
  4. $S2 and S3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
its charge is independent.
it is responsible for the stability of nuclei
The range of strong nuclear force is very small, of about nuclear dimensions $(10^{-15}m)$.
Multiple choice

Which subatomic particle has a negative charge?

  1. Neutron

  2. Proton

  3. Electron

  4. Nucleus
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electrons are subatomic particles that carry a negative electric charge. Protons are positively charged, and neutrons have no charge.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Heavy hydrogen has __  neutron and  _ proton in the nucleus.

  1. 2 and 1

  2. 1 and 2

  3. 1 and 1

  4. 2 and 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Deuterium is called as a heavy hydrogen.
Heavy hydrogen $\left( _{ 1 }^{ 2 }{ D } \right) $ $=$ $1$ neutron
                                            $1$ proton
                                            ${ 1e }^{ - }$
Multiple choice physics electric fields introduction to electrostatic force electric force charging and discharging

Two lithium nuclei in a lithium vapour at room temperature do not combine to form a carbon nucleus- because:

  1. a lithium nucleus is more tightly bound than a carbon nucleus

  2. carbon nucleus is unstable particle

  3. it is not energetically favourable

  4. coulomb repulsion does not allow the nuclei to come very close
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Two lithium nuclei in a lithium vapor can combine only if vapor is heated to a very high temperature. so that the nuclei acquire high kinetic energy to penetrate the coulomb barrier. The vapor is also compressed to a very high pressure.

Multiple choice biology carbon cycling mineral coal carbon cycle coal and its products coal petroleum and petrochemicals

How much energy is produced when two$ _1H^2$ nuclei fuse to produce $ _1H^3$ and $ _1H^1$ ?

  1. 1.0 MeV

  2. 4.0 MeV

  3. 1000 MeV

  4. 3.3 MeV
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$4.0 MeV$
Energy released in most nuclear reactions is much larger than in chemical reactions, because the binding energy that holds a nucleus together is far greater than the energy that holds electrons to a nucleus. For example, the ionization energy gained by adding an electron to a hydrogen nucleus is $13.6 eV$—less than one-millionth of the $17.6 MeV$ released in the deuterium–tritium (D–T) reaction.  The complete conversion of one gram of matter would release $9\times10^{13}$ joules of energy. Fusion reactions have an energy density many times greater than nuclear fission; the reactions produce far greater energy per unit of mass even though individual fission reactions are generally much more energetic than individual fusion ones, which are themselves millions of times more energetic than chemical reactions. Only direct conversion of mass into energy, such as that caused by the annihilatory collision of matter and antimatter, is more energetic per unit of mass than nuclear fusion.
Multiple choice physics nuclei beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

When a $\beta^-$ particle is emitted from a nucleus, the neutron-proton ratio:

  1. is decreased

  2. is increased

  3. remains the same

  4. first (A) then (B)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$ _{A}^{Z}\textrm{X}$ $\rightarrow  _{A-1}^{Z}\textrm{Y} $  $+  \beta^{-1}$


So,  the neutron-proton ratio before emission $ = \dfrac{Z-A}{A}$

And, the neutron-proton ratio after emission $ = \dfrac{Z-A+1}{A-1}$
Since, $ \dfrac{Z-A+1}{A-1}$  $ >\dfrac{Z-A}{A}$
Therefore, B is correct option.

Multiple choice physics nuclei beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

A positron is emitted by radioactive nucleus of proton number $90$. The product nucleus will have proton number :

  1. $91$
  2. $90$
  3. $89$
  4. $88$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The given nuclear reaction is-

$ _{90}X \rightarrow   _{+1}e $  $+ $ $ _zY$ 
Using law of conservation of atomic (or proton) number:
$90 = 1 + Z$
$\implies$ $Z = 89$
Thus the product nucleus will have proton number $89$.